ctdb-scripts: Avoid shellcheck warnings SC2030, SC2031 (subshell vari…

…ables)

SC2030: Modification of VAR is local (to subshell caused by (..) group).
SC2031: VAR was modified in a subshell. That change might be lost.

Fix a related, incorrect comment.

Signed-off-by: Martin Schwenke <[email protected]>
Reviewed-by: Amitay Isaacs <[email protected]>

ctdb/config/events.d/60.nfs

@@ -80,6 +80,9 @@ nfs_check_service ()
 {
     _progname="$1"
 
+    # This sub-shell is created to intentionally limit the scope of
+    # variable values read from the .check files.
+    # shellcheck disable=SC2030
     (
 	# Subshell to restrict scope variables...
 
@@ -166,7 +169,10 @@ nfs_check_service ()
     ) || exit 1
 }
 
-# Uses: stop_service, start_service, debug_stuck_threads
+# Uses: service_stop_cmd, service_start_cmd, service_debug_cmd
+# This function is called within the sub-shell that shellcheck thinks
+# loses the above variable values.
+# shellcheck disable=SC2031
 nfs_restart_service ()
 {
     if [ -z "$service_stop_cmd" -o -z "$service_start_cmd" ] ; then